The Australian government warned today that the conflict in Syria poses new risks of homegrown extremism in Australia, with citizens returning radicalised after fighting there.

Attorney General "George Brandis" said the crisis which has left more than 130,000 dead and forced millions from their homes presented a "complex set of global security challenges" that extend far beyond the Syrian border.

Two men were arrested in Australia in December and charged with foreign incursion offences after fighting alongside rebel groups in Syria and there have been "several reported deaths of Australian citizens in Syria", Brandis told the inaugural Interpol Global Security and Counter-Terrorism Convention in Sydney.

He said "In Australia, like many other countries, we are witnessing a growing trend of citizens travelling offshore to engage in, or support terrorist activities or conflict".

Brandis noted that "these individuals not only potentially breach Australian laws and commit offences offshore, but upon their return to Australia they pose a significant national security risk".

He said "those who actively participate in combat or assist in the planning and facilitation of such activity can become radicalized and obtain new skills - including the ability to conduct an attack on Australian soil, radicalize others and impart knowledge and skills gained offshore".

The assessment echoes police warnings in Britain last week that anyone returning from Syria faced arrest, with 16 people detained on suspicion of terror offences so far this month after arriving back from the war-torn nation. That compares with 24 in the whole of 2013.

Scores of Europeans have already lost their lives in the bloody three-year conflict and hundreds more have joined the fighting, troubling the region's leaders.

He said there was a "real" threat of an extremist attack on Australian soil, with 23 people charged to date under anti-terror laws brought in after the September 11 attacks in New York.

Tactics had shifted to "lone-actor, smaller-scale, multi-mode attacks", the attorney-general added, creating "significant difficulties for law enforcement and intelligence agencies" in detecting and disrupting potential plots.

More than 110 Australians have died in extremist attacks since 2001, Brandis told the conference, including the suicide bombings on the Indonesian tourist island of Bali in 2002 and 2005 which killed 92 Australians.

Some 200 law enforcement officers from 60 nations are attending the Interpol event.